title: A strategy for conversion from subcutaneous to oral ketamine in cancer pain patients: effect of a 1:1 ratio.
abstract: BACKGROUND
  No consensus exists about the most appropriate dose ratio for conversion from parenteral to oral ketamine.
  
  
  OBJECTIVE
  To confirm that a 1:1 dose ratio is suitable for converting subcutaneous (s.c.) to oral ketamine in cancer patients.
  
  
  METHODS
  Patients with opioid poorly responsive cancer pain, who responded to 0.4, 0.6, or 0.8 mg s.c. ketamine bolus, were treated with 0.1, 0.15, or 0.2mg/kg/h ketamine infusion, respectively. Switching to the oral route, by applying a 1:1 dose ratio, was carried out in patients who experienced adequate pain relief and continued to need ketamine as a coanalgesic. Pain, somnolence, feelings of insobriety, confusion, and cardiovascular parameters were assessed throughout the process.
  
  
  RESULTS
  Twenty-nine patients were enrolled in the study. Ketamine infusion decreased pain intensity from severe to no pain or slight pain in 23 of 29 and six of 29 patients, respectively. The median of s.c. ketamine doses was 0.2mg/kg/h (range 0.1-0.5). After oral switching, 27 of 29 patients remained as successfully controlled as when receiving s.c. ketamine. The other two patients needed a slight dose ratio readjustment, to 1:1.3 and 1:1.5, to maintain pain control. The median of oral ketamine doses was 300 mg/day (interquartile range 240-382.5). Seven of 29 patients receiving s.c. ketamine developed moderate and transitory side effects, such as feelings of insobriety and somnolence. No side effects were present while receiving oral ketamine. No significant changes were observed in cardiovascular parameters.
  
  
  CONCLUSIONS
  A 1:1 dose ratio for conversion from s.c. to oral ketamine is safe and effective in cancer pain patients.
authors.affiliation: Palliative Care Unit and Research Institute, University Hospital La Candelaria, Canary Health Service, Tenerife, Spain. mabenros@gmail.com
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Benítez-Rosario
authors.forename: Antonio
authors.initials: A
authors.lastname: Salinas-Martín
authors.forename: Toribio
authors.initials: T
authors.lastname: González-Guillermo
authors.forename: Manuel
authors.initials: M
authors.lastname: Feria
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000700:Analgesics / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005157:Facial Pain / Q000175:diagnosis / Q000188:drug therapy* / Q000209:etiology*; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D007649:Ketamine / Q000008:administration & dosage*; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications* / Q000188:drug therapy*; D010147:Pain Measurement / Q000187:drug effects; D016896:Treatment Outcome
chemical_list: D000700:Analgesics; D007649:Ketamine